KB3171021 Fails with Code 851A0042

I am trying to install KB3171021 (SQL Server 2014 SP2) on my production SQL box.  It fails with Code 851A0042.

This is the only information in the Event Log: Installation Failure: Windows failed to install the following update with error 0x80070643: Microsoft SQL Server 2014 Service Pack 2 (KB3171021).

I have verified the system and SQL server program disk have space on them.

Regards,

Ray